Machine for sharpening lawn-mower blades



Patented June 22, 1920.

2 SHEETS-SHEET l.

lil

C. F. BROWN.

MACHINE FOR SHARPENING LAWN MOWER B'LDES.

APPLICATION FILED APR, I2. I9I9.

IIIII i.. 1 IIIIIIII- C. F; BROWN.

MACHINEDFOR SHARPENING LAWN MowER BLADES. APPLlCATION FILED APR. l2, |919.

1 ,3 44, l 68. Patented J une 22, 1920.

2 SHEETS-SHEET 2.

HLM

Hmmm

III IIIII 45 1 sectional-view showing one of the mountin s UNITED STATES PATENT oFFlcE.

x VCHARLES E. BROWN, or GREENE'V'IVLLE,TENNEssEE.

To all whom Maag concern: j

Be it known that I, CHARLES F. BROWN, a citizen of the United States, and a resident ofr Greeneville, in the county of Greene and State of Tennessee, have invented certain' new and useful improvements in Machines for Sharpening Lawn-Mower Blades; and I' do hereby declare the following to be afull, clear, an'd eXact description ofthe invention, such as will enable others skilled in the art to which vit appertains to make and use 'the same.

rljhis invention relates to improvements in. machines for sharpening lawn mower bladesfone object of the invention being to 'so construct' a machine of thischaracter that the'grinding means can be accurately adjusted relatively to the blade.. f

A further object is to provide a machine for sharpening or' grinding lawn *mower blades, which can be easily vand. accurately operated and controlled; which shall effec tually and quickly sharpen the blade, and in which suflicient turning movement shall be imparted to the blade to cause 'the Aspiral edge portion to be maintained in contact withA the grinding' wheel when the latter is moved in a direction parallel with the axis aboutwhichsaid blade rotates when in use.

With these and other objects in view, the invention consists in certain novel features of construction-and combinations of parts as hereinafter set forth andpointed out in the claims. Y f

In the accompanying drawings; Figure 1 is a view in elevation; Fig. 4 is a transverse sectional View with the grinding wheel and its mounting omitted. F ig. 5 is a detail view partly'in section showing one of the mountin s for' the shaft 39 of the cutter frame;

ig. k6`is a detail view showing the connection between the shaft 10 and the top plate of the carriage, and Fig. 7 is a detail for` the shaft 10 and the connection of` this mounting with ythe table. l

1 represents a table or support having a top 2 `made preferably of sheet steel and provided withtracks 3, 3, which latter may conveniently consist of metal bars having V-grooves to receive the V-shaped portions of guides 4, 4, secured to a carriage 5, so that the flatter can be moved longitudinally ofthe tableftop MACHINE ron SHARPENING Igiiwixr-rgrownivv BLADES.

I Speciication of Iietters Patent.' Patented June 1920,

Application iled April 12, 1919. Serial No. 289,524.

vplate 6 and is grooved for the accommodation of an adjusting rod 10,-longitudinal movement of the latter relatively to the top plate being prevented by collars 11 on said rod at respective'sides of the block 8. The forward end portion of the rodr 1() is threaded as at 12, and this threaded portion of the rod passes through a head 13 yon a pin 14, the latter being pivotally mounted in the bottom plate 6 andpassing,through an elongated slot l5 in the' top plate 7. The head 13 bears against the under .face of the bottom plate 6 and the'pin 14 is threaded to receive a nut 16 which bears against the upper face of the top plate 7 ,-the plates 6 and 7 being thus clamped together when the partsV shall have been properly adjusted.. The rear portion of the adjusting rod `10 passes freely throughV a block 17 normally clamped to the bottom plate 6 by Ymeansof a screwlS, the head 19 of which bears against Athe upper face of said bottom plate. klheiscrew -18 passes through Va slot 20 in the bottom plate and thisslot is curved concentric with the pivot pin Y14 so that when the clamping screw 18 and nut 16 are loosened, the top plate and they grinding mechanism located thereon as hereinafter explained, as well as the adjusting rod 10, may be moved on the pivot pin as 'a fulcrum to adjust the angularity of the grinding means relatively to the'work.

Mounted upon the top plate 6 of the carriage 5, near the forward portion of the latter, is a pedestal 21 provided with suitable bearings for the accommodation of the shaft 22 of a grinding wheel 23. A pulley 24 is secured to the shaft22 and receives motion,

byrmeans of a strap 25 from a pulley 26 on` the driven shaft of an electric motor 27 the latter lbeing suitably mounted on the top `plate of the carriage.

A Work-support 28 is mounted upon the table top 2 and may be of a length approximately the same as that of the table. This 'nuts'31," thus permitting said support to be adjusted relativelyto4 the' grinding means.

ing bolts pass,-whereby the brackets 32 can be adjusted lengthwise of the support and also laterally with respect thereto. The brackets 32 are made with socketed portions for the reception of the shanks 36 of work holders 37, the latter being normally held in fixed positions by means of set screws 38 engaging said Shanks. The work holders 37 each have a general pear or conical shape with a similarly shaped opening having its apex at its lower end. The openings of the work holders receive kthe shaft 39 of a bla-de or cutter frame such as commonly employed with lawn mowers and in which the blades are of spiral form. Theshaft ofthe cutter frame is prevented from displacement in its mountings in the work holders, by means of set screws 4() and longitudinal movement of said shaft will be prevented by collars 41 secured to said shaft by set screws 42 and engaging the work holders.

In order to provide simple means for moving the work support and work holders carried thereby, to adjust the work relatively to the grinding means, posts 43 are secured to the table top 2 and through these posts, screws 44 pass,said screws being swiveled to the slidable support 2S and provided at their free ends with hand wheels 45 to facilitate the operation of said screws.

A bracket 4G is secured to the pedestal 2l on which the grinding device is mounted and to this bracket, the arm 47 of an internally threaded clamping sleeve 48 is se cured. A vertically adjustable guide screw 49 passes through the sleeve 4S and its upper pointed end 50 is adapted to engage the spiral blade to be sharpened.

`Vhen the cutter frame shall have been mounted in the work holders and the several parts of the machine shall haveV been adjusted by means of the devices hereinbefore described, so that the edge portion of the blade to be ground is properly presented to the grinding wheel, the operator will move the carriage longitudinally of the table (a handle 51 being provided to facilitate such operation) and the motor will have, in the meantime, been put in operationto rotate the grinding wheel; As the carriage is moved forwardly, the engagement of the end 5() of the guide screw 49 with the blade being ground, will cause the cutter frame to turn ,on its axial mounting in the work holders and the edge of the spirally formedv blade will be thus'kept constantly and accurately in engagement with the rotating grinding wheel.

It will be observed that adjustment of the grinding device relatively to the blade may be elfectedby the adjusting rod 10, or by the guide screw 49, or a slight adjustment may be effected by permitting af springing action between the plates of the carriage by slightly loosening the means which normally secure these plates together.

Various slight changes might be made in the details of construction of myinvention without departing from the spirit thereof or limiting its scope and hence I do not wish to restrict myself to the precise details herein set forth.

Having fully, described my invention what I claim as new and desire to secure by Letters-Patent, is

l. In a sharpening machine, the combination with a table, and a carriage mounted thereon, of grinding means mountedon said carriage, an electric motor also mounted on said earriageand connected with said grinding means for operating the same, and work holding means adjustably mounted on said table relatively to the carriage.

2. In a sharpening machine, the combination with a support, ofa carriage mounted thereon andv comprising upper and lower plates adj ustably connected together, whereby one plate 4may be angularly adjusted relatively to the other, grinding means mounted on the upper plate of the carriage, and work holding means mounted on said` support in l a plane in front of the grinding means.

3. In asharpening machine, the combina-` tion with a support, `of a carriage mounted on said support and comprising upper and lower plates, grinding means mounted on the upper plate, an adjusting device movably connected with the lowerplate and means connecting said adjusting device with the upper plate, wherebythe upper plate ofthe carriage and the grinding means thereon may be angularly adjusted relatively tothe lower plate of said'carriage, and work holding means mounted on said support inya plane in front of said carriage. j

4. In a sharpening machine, the combination with a. support,of a carriage mounted on said support and comprising upper and lower plates, work holding means mounted on the support in a plane in front of said carriage, grinding means mounted on said carriage, means pivotally connecting the upper plate of the carriage with the; lowerV plate whereby the angularityof the grind ing means may be adjusted, and means for moving the upper plate on the lower plate for adjusting the grinding means in a direction toward the work.`

5. In a sharpeningmachine,` the combination with a support, of a carriage mounted on said'support, grinding means mounted on the carriage, said carriage comprising :lower and upperplates having openings, a

pivotal mounting `for the upper plate, and an adjusting rod connected with said pivotal mounting and with the upper and lower plates, whereby the upper plate may be turned to adjust the angularit of the grinding means and also adjuste relatively to the work, and means for clamping the upper plate to the lower plate.

6. In a sharpening machine, the combination with a support, of a carriage mounted thereon and comprising an upper plate having a straight slot and a lower plate having an opening and also a curved slot, a pin pivotally mounted in the lower plate and passing through the straight slot of the upper plate, a nut on said p1n, a part depending from the upperV plate and passing through the opening of the lower plate, a block under they lower plate, a clamping device connected with said block and passing through the curved slot of said lower plate, and an adjusting screw swiveled to the depending part on the upper plate and passin through the pivot pin and block connecte with the lower plate and having threaded connection with one of said parts, and grinding means mounted on the upper plate of the carriage.

7. In a sharpening machine, the combination with a support, of a carriage mounted thereon, grinding means mounted on said carriage, said carriage comprising an upper slotted plate and a lower plate having an opening and a curved slot, a pin pivotally mounted in the lower plate and having a head under the latter,` said pin being threaded and passing through the slot ot' the upper plate, a clamping nut on said pin,

' tion with grinding means, of work holding means comprising parts having inverted conical openings to receive the shaft or journals of the blade structure of a mowing machine, whereby bearings are provided in the lower portions of said parts for said shaft or journals, screws passing through the upper portions of said parts and adapted to engage said shaft'or journals and retain the c same accurately on the bearings in the lower portions of the conical openings in said f parts, and. means for effecting relative adjustments of the carriage and work holding means and for moving one of them relatively to the other to effect the sharpening of a blade.

In testimony whereof I have signed this specification in thepresence of two subscrib ing witnesses.

CHARLES E. BROWN Witnesses:

HENRY R. BAKER, CHAs. C. SMITH. 

